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Human neurovascular unit chip with a functional blood-brain barrier models brain-infection mechanism of a fungal meningitis pathogen

ABSTRACT: Reconstitution of a neurovascular unit model with blood-brain barrier (BBB) function is of great importance for drug development targeting cerebral diseases and study of brain disease mechanisms. In this study, we describe a human neurovascular unit chip designed by reconstituting necessary cellular and extracellular components in microfluidic devices. Dynamic three-dimensional co-culture of human cells (neural stem cells, brain microvascular endothelial cells, and brain vascular pericytes) in microfluidics with a stepwise unidirectional flow successfully established the chip with BBB-mimetic structural and functional features to be an effective barrier for drugs and cytokines. Furthermore, we showed the utility of the chip by modeling the neurotropic behaviors and BBB penetration process of a global fungal meningitis pathogen, Cryptococcus neoformans. This chip is the first in vitro experimental model for monitoring neurotropism of C. neoformans and would contribute to the investigation of various cerebral disorders, including microbial infectious diseases and their corresponding drug development.

ORGANISM(S): Homo sapiens

PROVIDER: GSE171937 | GEO | 2021/04/13

REPOSITORIES: GEO

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Project description:The blood-brain barrier (BBB) consists of specific physical barriers, enzymes and transporters, which together maintain the necessary extracellular environment of the central nervous system (CNS). The main physical barrier is found in the CNS endothelial cell, and depends on continuous complexes of tight junctions combined with reduced vesicular transport. Other possible constituents of the BBB include extracellular matrix, astrocytes and pericytes, but the relative contribution of these different components to the BBB remains largely unknown. Here we demonstrate a direct role of pericytes at the BBB in vivo. Using a set of adult viable pericyte-deficient mouse mutants we show that pericyte deficiency increases the permeability of the BBB to water and a range of low-molecular-mass and high-molecular-mass tracers. The increased permeability occurs by endothelial transcytosis, a process that is rapidly arrested by the drug imatinib. Furthermore, we show that pericytes function at the BBB in at least two ways: by regulating BBB-specific gene expression patterns in endothelial cells, and by inducing polarization of astrocyte end-feet surrounding CNS blood vessels. Our results indicate a novel and critical role for pericytes in the integration of endothelial and astrocyte functions at the neurovascular unit, and in the regulation of the BBB. The brain microvascular fragments were isolated from mice with different genotypes, each represented by 3-4 biological replicates. Genotypes 1-2: Platelet derived growth factor-B (PDGF-B) retention-motif knockout (pdgfbret/ret) represent the pericyte-deficient situation, and the heterozygous mice (pdgfbret/+) are used as controls. Genotypes 3-4: Hypomorphic PDGF-B mutants that rescue pdgfb-/- null mice, in which a one copy of a conditionally silent human PDGF-B transgene targeted to the Rosa 26 locus (R26P) is turned on by endothelial-specific expression of Cre recombinase. In this data set these mice are named as Tie2Cre, R26P+/0, pdgfb-/- (representing the pericyte-deficient situation). Mice wt for pdgfb (pdgfb+/+) and carrying one silent copy of R26P (R26P+/0), are used as controls. Genotype 5: Adult Notch3+/+ wildtype (WT).

Project description:With advances in single-cell genomics, molecular signatures of cells comprising the brain vasculature are revealed in unprecedented detail, yet the ageing-associated cell subtype transcriptomic changes which may contribute to neurovascular dysfunction in neurodegenerative diseases remain elusive. Here, we performed single-cell transcriptomic profiling of brain endothelial cells (EC) in young adult and aged mice to characterize their ageing-associated genome-wide expression changes. We identified zonation-dependent transcriptomic changes in aged brain EC subtypes, with capillary ECs exhibiting the most transcriptomic alterations. Pathway enrichment analysis revealed altered immune/cytokine signaling in ECs of all vascular segments, while functional changes impacting the blood-brain barrier (BBB) and glucose/energy metabolism were most prominently implicated in ECs of the capillary bed – the primary site where ECs and other neurovascular unit (NVU) cell types closely interact and coordinate to regulate BBB and cerebral blood flow in health and diseased conditions. Furthermore, an overrepresentation of Alzheimer’s disease (AD)-associated genes identified from GWAS studies was evident among the human orthologs of differentially expressed genes of aged capillary ECs but not other EC subtypes. Importantly, for numerous EC-enriched differentially expressed genes with important functional roles at the BBB and/or association with AD, we found concordant expression changes in human aged or AD brains. Finally, we demonstrated that treatment with exenatide, a glucagon-like peptide-1 receptor (GLP-1R) agonist, strongly reverses transcriptomic changes in ECs and largely reduces BBB leakage in the aged brain. Thus, our study revealed novel vascular ageing-associations of AD in the brain capillary endothelium, and provides insights into detailed transcriptomic alterations underlying brain EC ageing that are complex with subtype specificity yet amenable to pharmacological interventions.

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Human neurovascular unit chip with a functional blood-brain barrier models brain-infection mechanism of a fungal meningitis pathogen

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